Question 725581
Let 'n' and 'p' are the present ages of nandu and panna respectively.
Let 's' be the present age of subha.

3 years ago,

n' = n - 3
p' = p - 3
(n' + p')/2 = 18
(n+P-6)/2 = 18
(n+p) = 42

Present average of 3 girsl = (n + p + s) /3 = 22
(42 + s)= 66
s = 22 years